The hardness and thermal properties of diamond are but two of the characteristics that make it useful in a variety of industrial components. Initially, natural diamond was used in a range of abrasive applications. With the ability to synthesize diamond by high pressure/high temperature (HP/HT) techniques utilizing a catalyst/sintering aid under conditions where diamond is the thermodynamically stable carbon phase, a variety of additional products found favor in the marketplace. Polycrystalline diamond compacts, often supported on a tungsten carbide base, further extended the diamond product line. However, the requirements of high pressure and high temperature have served as a limitation, e.g., in product configuration.
Recently, industrial effort directed toward the growth of diamond at low pressures, where it is metastable, has increased dramatically. Although the ability to produce diamond by low-pressure synthesis techniques has been known for decades, drawbacks including extremely low growth rates prevented wide commercial acceptance. Recent developments have led to higher growth rates, thus spurring further interest in the field. Additionally, the discovery of an entirely new class of solids, known as "diamond-like" carbons and hydrocarbons, is an outgrowth of such recent work.
Low pressure growth of diamond has been dubbed "chemical vapor deposition" or "CVD" in the field. One of the common techniques involves the use of a dilute mixture of hydrocarbon gas (typically methane) and hydrogen wherein the hydrocarbon content usually is varied from about 0.1% to 2.5% of the total volumetric flow. The gas is introduced into a reactor that contains a hot tungsten filament which is electrically heated to a temperature ranging from between about 1750.degree. to 2400.degree. C. The gas mixture dissociates at or near the filament surface and diamond forms on a hot substrate placed near the tungsten filament.
Whether natural or man-made, the same characteristics that make diamond so useful are occasionally also its greatest drawback. For example, the extreme hardness of diamond makes shaping or smoothing difficult. It would therefore be desirable to provide a method wherein diamond and diamond films may be shaped or smoothed more efficiently than the currently available procedures allow.